I. KIRIK: WELDABILITY OF Ti6Al4V TO AISI 2205 WITH A NICKEL INTERLAYER ...
353–356
WELDABILITY OF Ti6Al4V TO AISI 2205 WITH A NICKEL
INTERLAYER USING FRICTION WELDING
PREIZKU[ANJE VARIVOSTI PRI VARJENJU S TRENJEM Ti6Al4V
IN AISI 2205 Z VMESNO PLASTJO NIKLJA
Ihsan Kirik
Batman University, Faculty of Engineering and Architecture, Department of Metallurgical and Materials Engineering, 72060 Batman, Turkey
alihsankirik@gmail.com
Prejem rokopisa – received: 2015-02-12; sprejem za objavo – accepted for publication: 2015-05-04
doi:10.17222/mit.2015.039
The aim of this study was to friction weld dissimilar metals, i.e., Ti6Al4V to duplex stainless steel, with and without a nickel
interlayer using a new method. The metallographic examinations of the weld were carried out and the strength of the joints was
determined with tensile tests. The experimental results indicate that the Ti6Al4V and duplex stainless steel could be joined with
a nickel interlayer. The highest tensile strength (605 MPa) was obtained and the tensile strength of the joint was significantly
increased with an increase of the rotation speed and the friction pressure.
Keywords: friction welding, titanium alloy, duplex stainless steel, nickel interlayer
Namen te {tudije je varjenje s trenjem razli~nih materialov Ti6Al4V in dupleks nerjavnega jekla, z in brez vmesne plasti niklja,
z uporabo nove metode. Izvr{eni so bili metalografski preizkusi zvara. Rezultati preizkusov ka`ejo, da je z vmesnim slojem
niklja mogo~e spajati Ti6Al4V in dupleks nerjavno jeklo. Z nara{~anjem hitrosti vrtenja in pritiska pri trenju je mogo~e dose~i
najvi{jo natezno trdnost (605 MPa), hkrati pa nara{~a tudi natezna trdnost spoja.
Klju~ne besede: varjenje s trenjem, titanova zlitina, dupleks nerjavno jeklo, vmesni sloj niklja
1 INTRODUCTION
Materials such as low-carbon steels, ceramics and
composites that are problematic and difficult to join
using traditional welding methods can be joined by
friction welding (FW). One of the biggest advantages of
FW is the production of a new material from pairs of
dissimilar materials.1–2 FW is an important manu-
facturing technique used in the machine construction and
hydraulic industry, the automotive industry, and the
industry for cutting and drilling tools. This technique has
an important application area in welding technology, as
it can join materials with different compositions if their
sizes and shapes are appropriate, it does not have a
limited melting event and it has a very low welding
failure.3–5
The joinability of Ti and its alloys to steels is
extremely important because more and more of these
metals are used together.6 When Ti alloys and stainless
steels join mechanically, many intermetallic phases and
different tension concentration areas occur at the inter-
mediate of the joint, which then causes embrittlement
and cracking.7 When Ti directly welds to the stainless
steel, intermetallic compounds such as FeTi and Fe2Ti
can occur at the joining area due to Ti and Fe having
very little fusion capabilities. Besides, TiC may form
since Ti is a strong carbide-forming element and also
occurrences of these compounds cause a crispiness in the
joining area. On the other hand, cracks may occur in the
welding area due to the difference in the thermal
conductivity between the Ti alloy and the steel. To avoid
these negatives, the Ni interlayer diffusion welding
method was used to combine the TiC4, the Ti alloy and
the stainless steel, and sound joints were obtained, which
had high strengths.8 The Ti-6Al-4V alloy and a micro-
duplex stainless steel (AVESTA 2205) were joined using
the diffusion-welding technique, and good results were
obtained at temperatures as low as 800 °C in 30 min.9
Aleman et al.10 studied pure Ti and 316L stainless steel
using the diffusion-welding technique and they stated
that the -phase was observed on the stainless-steel side,
Fe2Ti and FeTi in the inner side, and Fe2Ti4O oxide on
the Ti side. Muralimohan et al.11 welded Ti and 304L
stainless steel by FW and through a nickel interlayer,
which is deposited by electroplating on stainless-steel
substrates with a range of 100±3 μm. The joining of
dissimilar materials such as aluminium, titanium, magne-
sium and their alloys to stainless steels was reported in 1–14,
but very limited studies are reported for titanium and its
alloy to stainless steel using FW. Moreover, using an
interlayer in FW is very limited, because it is difficult to
keep the intermediate layer in the intermediate zone.
TiAl and AISI 4140 steel were joined through FW with a
copper insert layer and two-step joining of the FW was
carried out to complete the joints by W. B. Lee et al.12
Madhusudhan and Venkata13 investigated the role of the
nickel insert layer in the FW of maraging steel to low-
alloy steel. To incorporate nickel as an interlayer, marag-
Materiali in tehnologije / Materials and technology 50 (2016) 3, 353–356 353
UDK 621.791:669.295:669.055:669.24 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 50(3)353(2016)
ing steel and nickel were welded first. To maintain the
5-mm length of interlayer the nickel was cut. Sub-
sequently, low-alloy steel was welded on the nickel side
of the joint.
The literature examined for using an insert layer in
FW joining revealed two stages or the interlayer is kept
at the interface using a different method. For this reason,
the goal of this study is the successful joining of the
Ti6Al4V titanium alloy and the AISI 2250 duplex stain-
less using FW single stage and with a nickel interlayer
using a new technique. The strengths of the joints were
determined by tensile tests and compared with those of
base materials. Then, the microstructures in the welding
zone were obtained and investigated using macro- and
micro-photographs.
2 EXPERIMENTAL PROCEDURES
In this study, three materials with different properties
were used in order to be joined using friction welding.
The analysed chemical compositions of the materials are
illustrated in Table 1. The duplex stainless steel and the
Ti6Al4V alloy bars were provided commercially with a
12-mm diameter and were processed on a turning lathe
machine according to the sizes shown in Figure 1a.
Firstly, during the FW the most difficult stage while
using the insert layer is to keep it at the interface. Thus,
to avoid the escape of the interlayer, the surface of the
duplex stainless steel is processed with a 10 mm dia-
meter and a 3 mm depth, as shown in Figure 1a. Later,
the nickel interlayer was placed on the forehead of the
duplex stainless steel with the help of a press and then
the welding was performed in a continuously driven FW
machine using the parameters given in Table 2. After the
FW, in order to determine the microstructural changes to
the samples that were friction welded, the axial cross-
section of the joint was achieved by abrasive cutting and
attached for polishing, and then the samples were etched
in a chemical solution for the metallographic examina-
tion. The microstructure analyses of the joints were
carried out with an optical microscope, and the scanning
electron microscopy (SEM) and quantitative chemical
analyses were performed with an energy-dispersive
spectrometer (EDS). The friction-welded joints, with and
without an interlayer, were tested for their tensile
strength.
I. KIRIK: WELDABILITY OF Ti6Al4V TO AISI 2205 WITH A NICKEL INTERLAYER ...
354 Materiali in tehnologije / Materials and technology 50 (2016) 3, 353–356
Table 1: Chemical compositions of the test materials, in mass fractions (w/%)
Tabela 1: Kemijska sestava preiskovanih materialov, v masnih dele`ih (w/%)
Materials Alloying elements, in mass fractions (w/%)
Ti C Mn P Si Cr Al Ni Cu V Fe
Ti6Al4V Bal = 0.08 – – 0.15 – 5–6.50 – – 3.5–4.5 = 0.40
AISI 2205 – 0.01–0.03 1.68–2.00 0.026 – 21–23 – 3.37 – – Bal
Nickel – – 0.007 – – – – Bal 0.01 – –
Table 2: The process parameters, used in the FW and the tensile test results according to these parameters
Tabela 2: Procesni parametri, uporabljeni pri FW in rezultati nateznega preizkusa pri teh parametrih
Sample
No.
Welding parameters
Rotation speed
(m–1)
Fric. time
(s)
Fric. press.
(MPa)
Forging
pressure (MPa)
Forging time
(s)
Without
Interlayer
With Interlayer
Ten. Stren.
(MPa)
N1 1500 6 150 200 4 Failed 380
N2 1500 6 125 200 4 Failed 326
N3 1500 6 100 200 4 Failed –
N4 1800 6 150 200 4 Failed 420
N5 1800 6 125 200 4 Failed 605
N6 1800 6 100 200 4 Failed 180
Nickel – – – – – – 450
AISI 2205 – – – – – – 956
Ti6Al4V – – – – – – 870
Figure 1: Schematic illustration of friction welded Ti6Al4V and AISI
2205 using: a) nickel interlayer, b) macrograph of cross-section of
friction welded N5 sample
Slika 1: Shematski prikaz zvara pri trenju Ti6Al4V in AISI 2205: a) z
uporabo vmesnega sloja niklja, b) makroposnetek preseka vzorca N5,
zvarjenega s trenjem
3 RESULTS AND DISCUSSION
3.1 Examinations of microstructure
A macro image of the FW joint N5 sample is shown
in Figure 1b. It is evident that the joint is unsymmetrical
and the flash dimensions of the Ti alloy are much larger
than the stainless steel due to the decrease of the tensile
yield strength of the Ti alloy with temperature being
much more significant than that of duplex stainless steel,
although at room temperature the situation is exactly
reversed.15
The optical photographs taken from the FW joint N5
sample shows that the Ti6Al4V/AISI 2205 materials
were successfully friction welded using a nickel
interlayer (Figure 2). It is clear that there is a structural
disorder and differently directed grains on the Ti6Al4V
side near the nickel interlayer. Moreover, the FW of
dissimilar metals, Ti6Al4V to duplex stainless steel,
without an interlayer were tried so many times with
different parameters, but the joints were not achieved due
to brittle phase reaction and volume expansion.
The SEM micrograph for the N4 sample joined at a
rotation of 1800 min–1, a 6-s friction time, a 150 MPa
friction pressure, a 200 MPa forging pressure and a 4-s
forging time is illustrated in Figure 3. From the micro-
graph it is clear that at the nickel and Ti6Al4V interface
there were three different zones: (-Ti + -Ti) of
Ti6Al4V, -phase and intermetallic phase in interface
zone, nickel zone and invisible stainless steel zone.
From 14, when Ti alloys and the stainless-steel joint FeTi
and Fe2Ti intermetallic phase occurred. Also, these
phases adversely affect the quality of the joint. To elimi-
nate the effects of this occurrence a nickel interlayer was
used and the results confirmed that this is necessary. The
concentrations of the elements across the interface zone
are shown in Table 3 and the EDS graph is presented in
Figure 3. From the EDS results of the N4 sample diffe-
rent amounts of Al, Si, Ti, V, Ni and Mo were obtained,
but in the nickel some oxygen is obtained. As shown in
Table 3, Ti and Ni have a high degree of diffusion in the
approximately 15-μm region. Also, Ti diffused from
Ti6Al4V to the nickel interlayer, the nickel diffused into
the Ti alloy over the same distance. The FW of dissimilar
materials with a nickel interlayer exhibits a wider pla-
sticized zone in the middle of the welding interface. The
variation of the alloying elements at the mutual interfe-
rence is on account of the thermo-plastic stirring and the
diffusion mechanism.
Table 3: Elementary variation rates from EDS analyses across the
welding interface of the N4 sample
Tabela 3: Spreminjanje vsebnosti elementov dolo~ena z EDS analizo
preko zvara vzorca N4
Alloying
elements
(w/%)
EDS points
1 2 3
O – – 12.47
Al 6.799 5.755 –
Si – 0.799 –
Ti 88.087 60.583 0.181
V 4.025 1.950 –
Ni 0.910 30.705 87.160
Mo 0.189 0.208 0.188
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Materiali in tehnologije / Materials and technology 50 (2016) 3, 353–356 355
Figure 3: SEM photograph of the interface of the N4 sample and the
EDS analysis
Slika 3: SEM-posnetek vmesnega sloja pri vzorcu N4 in EDS-analiza
Figure 2: Optical microstructure of the interface of the N5 sample
Slika 2: Mikrostruktura vmesnega sloja pri vzorcu N5
3.2 Tensile testing
The tensile strength of the joints was determined, as
seen in Table 2, based on two different rotation speeds
(1500 min–1 and 1800 min–1), three different friction
pressures (100, 125 and 150) MPa, a constant friction
time (6 s), a forging time (4 s) and a forging pressure
(200 MPa). The highest tensile strength (605 MPa) was
obtained for the N5 sample. The tensile strength was
increased by increasing the rotation speed with a
constant friction time and pressure, and increasing the
tensile strength results in heat input and a high plastic
deformation. The fracture surface of the tensile test
sample N5 is characterized with SEM to understand the
failure mechanism. Figure 4 illustrates the fracture-
surface morphologies taken from the centre of N5. It is
clear that the fracture surface of the joint indicates a
brittle cleavage fracture for Ti6Al4V/AISI 2205 stainless
steel for different materials welding by FW using a
nickel interlayer.
4 CONCLUSION
The effects of a nickel interlayer and the process
parameters on the microstructure and tensile strength of
friction welds between a Ti6Al4V alloy and AISI 2205
duplex stainless steel with and without an interlayer were
studied. The following results were achieved:
Ti6Al4V and AISI 2205 were successfully joined by
FW using a nickel interlayer.
In the event of FW between the Ti6Al4V and AISI
2205 the soundness of the joints was increased with a
nickel interlayer and the rotation speed; but without an
interlayer cracks occurred and it was not joined due to a
brittle phase reaction and the volume expansion.
The highest tensile strength (605 MPa) was obtained
for the N5 sample joined at 1800 min–1, a 6-s friction
time, 125 MPa of friction pressure, 200 MPa of forging
pressure and a 4-s forging time. The tensile strength was
increased when the rotation speed and the friction
pressure increased.
5 REFERENCES
1 N. Özdemir, Investigation of the mechanical properties of fric-
tion-welded joints between AISI 304L and AISI 4340 steel as a
function rotational speed, Materials Letters, 59 (2005), 2504–2509,
doi:10.1016/j.matlet.2005.03.034
2 I. Krik, N. Özdemir, Weldability and joining characteristics of AISI
420/AISI 1020 steels using friction welding, Int. J. of Mat. Research,
8 (2013), 769–776, doi:10.3139/146,110917
3 M. Sahin, Characterization of properties in plastically deformed
austenitic-stainless steels joined by friction welding, Materials and
Design, 30 (2009), 135–144, doi:10.1016/j.matdes.2008.04.033
4 V. V. Satyanarayana, G. M. Reddy, T. Mohandas, Dissimilar metal
friction welding of austenitic-ferritic stainless steels, J. of Mat. Proc.
Tech., 160 (2005) 2, 128–137, doi:10.1016/ j.jmatprotec.2004.05.017
5 H. Ates, M. Turker, A. Kurt, Effect of friction pressure on the pro-
perties of friction welded MA956 iron-based superalloy, Materials
and Design, 28 (2007) 3, 948–953, doi:10.1016/j.matdes.2005.
09.015
6 M. Ghosh, S. Chatterjee, Effect of interface microstructure on the
bond strength of the diffusion welded joints between titanium and
stainless steel, Materials Characterization, 54 (2005) 4–5, 327–337,
doi:10.1016/j.matchar.2004.12.007
7 M. Ghosh, S. Chatterjee, Characterization of transition joints of
commercially pure titanium to 304 stainless steel, Materials Charac-
terization, 48 (2002) 5, 393–399, doi:10.1016/S1044-5803(02)
00306-6
8 P. He, J. C. Feng, B. G. Zhang, Y. Y. Qian, A new technology for
diffusion bonding intermetallic TiAl to steel with composite barrier
layers, Materials Characterization, 50 (2003) 1, 87–92, doi:10.1016/
S1044-5803(03)00122-0
9 N. Orhan, T. I. Khan, M. Eroðlu, Diffusion bonding of a microduplex
stainless steel to Ti–6Al–4V, Scripta Materialia, 45 (2001) 4,
441–446, doi:10.1016/S1359-6462(01)01041-7
10 B. Aleman, I. Gutiérrez, J. J. Urcola, The use of kirkendall effect for
calculating intrinsic diffusion coefficients in a 316L/Ti6242 diffusion
bonded couple, Scripta Materialia, 36 (1997) 5, 509–515,
doi:10.1016/S1359-6462(96)00414-9
11 C. H. Muralimohan, V. Muthupandi, K. Sivaprasad, Properties of
friction welding titanium-stainless steel joints with nickel interlayer,
Procedia Materials Science, 5 (2014), 1120–1126, doi:10.1016/
j.mspro.2014.07.406
12 W. B. Lee, Y. J. Kim, S. B. Jung, Effects of copper insert layer on the
properties of friction welded joints between TiAl and AISI 4140
structural steel, Intermetallics, 12 (2004) 6, 671–678, doi:10.1016/
j.intermet.2004.02.004
13 G. Madhusudhan Reddy, P. Venkata Ramana, Role of nickel as an
interlayer in dissimilar metal friction welding of maraging steel to
low alloy steel, J. of Mat. Process. Tech., 212 (2012), 66–77,
doi:10.1016/j.jmatprotec.2011.08.005
14 B. Kurt, N. Orhan, E. Evin, A. Çalik, Diffusion bonding between
Ti–6Al–4V alloy and ferritic stainless steel, Materials Letters, 61
(2007) 8–9, 1747–1750, doi:10.1016/j.matlet.2006.07.123
15 P. Li, J. Li, M. Salman, L. Liang, J. Xioeng, F. Shang, Effect of
friction time on mechanical and metallurgical properties of
continuous drive friction welded Ti6Al4V/SUS321 joints, Materials
and Design, 56 (2014), 649–656, doi:10.1016/ j.matdes.2013.11.065
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356 Materiali in tehnologije / Materials and technology 50 (2016) 3, 353–356
Figure 4: SEM photograph of fractured surface of N5 sample
Slika 4: SEM-posnetek povr{ine preloma vzorca N5